I'm not sure if PowerPoint will give you what your looking to do.
Don't get me wrong, you can add multimedia files and have them auto play when a powerpoint starts but I'm not sure how you pull excerpts out of it to make it do that.
You may want to check out other products like http://windows.microsoft.com/en-us/windows/movie-maker
I posted the link to this because it's free and does work. It allows you to combine multiple multimedia files together and stitch them together. I believe you can even output it as a file or even ready for a DVD but I'm not so sure on this last statement though.
*if the post above has answered the question, please mark the topic as solved.
**All "answers" and responses are offered "as is" and my opinion. There is no implied support or guarantee by the ITProTV team.